Typical adhesive systems for applying hot-melt adhesives to a substrate include a melter that provides a supply of hot-melt adhesive. The adhesive can flow from the melter through hoses to any number of applicators, which each are capable of applying the adhesive to a substrate. However, the melter and applicators are typically spaced apart, which causes the adhesive to travel a distance between the melter and the applicators. As the distance between the melter and applicators increases, so does the actual volume of the soft inner core as an adverse reaction to changes in pressure. As a result, when the adhesive ultimately reaches the applicators, the pressure is different than intended by the operator of the adhesive system. The pressure control device being located a great distances away from the applicator increases the reaction time of the pressure control device to adequately control pressure at the applicator as hose lengths increase. This variability in pressure can cause negative consequences, such as hammerhead, inconsistent add-on rates per product, and burn-through on heat-sensitive substrates. Additionally, the ability to add additional flow streams based upon increased applicator requirements can be limited. In conventional systems, for example, if a melter has an output capacity sufficient to supply four applicators, and the existing pump system includes four pumps, an additional melter must be utilized to supply any additional flow streams.
To help reduce pressure variation at the point of application, pumps can be attached to the adhesive system between the melter and the applicators. These pumps conventionally take the form of single or multi-stream gear pumps having a common drive shaft to power the pumps. The gear pumps can be attached to a unitary manifold. These gear pumps function to further control the pressure of the adhesive in the applicator system. However, pumps utilizing common drive shafts have drawbacks.
For example, if an operator desires to change the motor speed of a dual-stream pump in a system utilizing a common drive shaft (referring to Remote Metering Devices), the operator will inherently change the flow output of both streams. This decreases flexibility regarding controlling individual flow streams.
Therefore, there is a need for a remote metering device that allows for individually controllable flow paths, and/or the ability to add additional pumps as needed without requiring additional melters.